android判断网络是否可用

public static boolean isNetworkAvailable(Context context) { 
        if(context != null){
             ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); 
             NetworkInfo mNetworkInfo = cm.getActiveNetworkInfo(); 
             if (mNetworkInfo != null) { 
                return mNetworkInfo.isAvailable(); 
            } 
        }
       return false;
    }